Chagas' disease is one of the most deadly infectious diseases in the American continent, and is caused by the protozoan parasite Trypanosoma cruzi. Over 11 million people are infected, and about 120 million individuals are at risk of acquiring the disease. Up to 100,000 migrants from endemic countries living in the U.S. are thought to be infected with T. cruzi, and represent a latent risk for recipients of blood components, and organs. Currently, only one partially effective drug is available for the treatment of Chagas' disease. There is no human vaccine against T. cruzi. The overall goal of this proposal is to identify and validate major immunodominant antigens that are ubiquitously expressed on the cell surface of mammal-dwelling stages of T. cruzi for the development of new immunotherapeutic approaches to prevent or treat Chagas' disease. To achieve this, the following specific aims are proposed: Specific aim # 1. Expression proteomics of the plasma membrane of trypomastigote and intracellular amastigote forms of T. cruzi. Our primary goal is to identify by proteomic analysis the major proteins and glycoproteins expressed on the cell surface of the mammal-dwelling stages in different phylogenetic lineages and strains of T. cruzi. Specific aim # 2. Functional proteomics of the cell surface of trypomastigote and intracellular amastigote forms of T. cruzi to identify and validate novel antigenic targets for vaccination. We will perform an extensive immunological analysis of selected surface (glyco)proteins found in specific aim # 1, to validate them as antigenic targets for experimental vaccination. We will identify proteins that are able to induce efficient humoral and celullar immune responses in mice. Finally, we will perform experimental immunization with the two best antigenic targets, followed by challenge with T. cruzi to evaluate the protection against the parasite. Overall significance: We believe that this project will result in the identification of immunodominant antigenic targets on the cell surface of mammal-dwelling stages of T. cruzi and in the development of new immunotherapeutic approaches for prevention and treatment of Chagas' disease.